hi ,,maybe some of this will help...
GV-R787OC-2GD Core Clock 1100MHz (Std 1000) Factory OCe'd to 1100MHz Ports HDMI 1 DVI-I 1 Mini DisplayPort 2 Limited Warranty period (parts): 3 years Tri fan cooling Dimensions H= 38mm, L=285 mm, W=126 mm Gigabyte website shows 600W PSU as the minimum.
XFX - FX-787A-CDFC Core Clock 1000MHz (can be overclocked) Limited Lifetime Warranty period Ports 1 x HDMI DisplayPort 2 x Mini DisplayPort 2 x DVI (1 Single Link, 1 Dual Link) Twin Fan cooling Dimension 9.5" x 4.4" x 1.5" 500 W PSU minimum
On one hand the Gigabyte card has the factory OC and tri-cooled with a 3 year warranty (if that is important to you) The length of cards may be more important for your rig / config.Or the ports?
Might at well look at the Sapphire card in the HD 7870 series too. Had very good cards from Sapphire before, the included kit is a bit nice too plus the Sapphire Club.
http://www.newegg.com/Product/Product.aspx?Item=N82E16814102996
Very nice cards and a pretty darn good deal with the included games.[:)]
By the way what CPU you got ? and what PSU you have ? you likely should have an 80+ 750W PSU